Generally these are the most common 2 options:
1) If the product is found to be faulty the product is replaced with the same or equivalent model.
2) If you want a refund there is a 10%-15% restocking fee as the product has to be resold as "open-box" instead of "new".

You might have other options depending on the brand and circumstances but from my (very limited) experience the 2 options above are what I expect.